This invention relates to an assembly of components forming a hot runner system for molds in injection molding machines. These components include a central inlet member, a number of sprue bushes and runners for distributing a flow of viscous plastics composition from the central inlet to the individual sprue bushes. In the runner system sprue bushes may be located relatively close to the central inlet and may be located at a greater distance from the central inlet. More particularly, the invention relates to a runner system in the form of an assembly which comprises a number of standard components of identical construction. The system is intended primarily for molds having a plurality of mold cavities and for injection molding of articles of relatively large dimensions and may comprise a great number of sprue bushes which may be arranged in linear and in parallel arrays. The term central inlet implies, in general, that the inlet is common to a plurality of runners, but does not necessarily mean that it is the geometrical center of the system.